The fan coil units of central air conditioning should be cleaned and maintained regularly, no matter in winter or summer. Because the fan coil units run for a long time, there will be a lot of dust in the tuyere. If the fan coil units are not cleaned and maintained regularly, the service life of the fan coil units will be affected. If the cleaning is not clean, it will also affect the health.

According to the survey results of EPA and Danish University of Technology in the United States and Europe, 42%-53% of indoor air pollution comes from air conditioning and ventilation system because of long-term operation and improper cleaning. The main pollutants in the ventilation system are particulate matter and microorganisms. You can't see them with your eyes, so you must be careful when you wash them.

中央空调风机盘管系统承载着现代楼宇的空气新陈代谢，是楼房内名副其实的核心器官――“肺”。

The central air conditioning fan-coil system carries the air metabolism of modern buildings, and is the core organ of the building - lung.

中央空调的通风系统是长期积累下来的卫生死角，其面积远大于我们平时能够清洗到的机组面积。

The ventilation system of central air conditioning is a long-term accumulation of sanitary dead angle, its area is far larger than the unit area that we can usually clean.

Although long-term cleaning, but not clean, not clean air ducts provide a stable environment for harmful substances, they will continue to breed and spread widely in the indoor with all kinds of ventilation ducts, causing secondary air pollution in the air conditioning, building air conditioning and ventilation system caused by human health hazards and diseases. Up to dozens of species. According to the degree of harm to human body, the nature of the disease and the pathogen of the disease, it can be roughly divided into three categories: acute infectious diseases (such as Legionella disease, SARS); allergic diseases (including allergic pneumonia, humidifier fever, etc.); and "sick building syndrome".

The dust samples collected from the central air-conditioning ventilation system were analyzed by microscopy. The main components were dust gravel, carbon substances, crystals, fibers, coating sheets, corroded materials on the inner wall of the falling duct, etc. In addition, some insect corpses were mixed in them. Once there are bacteria, fungi, yeasts and other microorganisms in the dust, it is easy to cause allergies or respiratory diseases.